1. Field of the Invention
The present invention relates to a circuit-component transferring apparatus which includes a component sucker for sucking and holding a circuit component, such as an electric-circuit or an electronic-circuit component, and which transfers the circuit component held by the component sucker, and particularly to the art of changing a pressure in the component sucker.
2. Related Art Statement
Japanese Patent Application laid open for inspection under Publication No. 6(1994)-342998 discloses a circuit-component ("CC") transferring device which includes a component sucker for sucking and holding a circuit component and which transfers the circuit component held by the component sucker. The CC transferring device is employed in a CC mounting system. The CC transferring device includes an intermittently rotatable body which is intermittently rotatable about an axis line thereof and which is equipped with a plurality of upward and downward movable members on a circle whose center rides on the axis line, such that the movable members are equiangularly spaced from each other about the axis line and such that each of the movable members is movable upward and downward. The plurality of movable members holds a plurality of component suckers, respectively. When the rotatable body is intermittently rotated, the component suckers are sequentially moved to a component sucking position, as one of a plurality of stop positions, where each of the component suckers is moved downward by downward movement of a corresponding one of the movable members so as to suck a CC. After the sucking of CC, each component sucker is moved by the intermittent rotation(s) of the rotatable body to a component mounting position as another stop position where each component sucker is moved downward by the downward movement of the corresponding movable member so as to mount the CC on a circuit substrate ("CS") such as a printed circuit board ("PCB").
When each component sucker sucks a CC, a negative pressure is supplied to each component sucker; and when each component sucker mounts the CC on a CS, the negative pressure is removed therefrom. The supplying and removing of negative pressure are performed for each one of the component suckers, independent of the other component suckers. To this end, each of the movable members is equipped with a pressure switching valve. At the component sucking position, each of the pressure switching valves is switched from its negative-pressure ("NP") removing state in which the switching valve removes a NP from the corresponding component sucker and causes the sucker to release a CC, to its NP supplying state in which the switching valve permits the NP to be supplied to the sucker and causes the sucker to suck a CC. This switching is carried out by a switching assisting member which is provided on the corresponding movable member, and a switching member which is provided at the component sucking position. More specifically described, when each of the movable members is moved downward, the corresponding switching assisting member moves the switching member, thereby causing the switching of the corresponding pressure switching valve. Meanwhile, at the component mounting position, each pressure switching valve is switched from its NP supplying state to its NP removing state. This switching is carried out by another or second switching member which is provided at the component mounting position. More specifically described, when each movable member is moved downward, the second switching member engages the corresponding pressure switching valve, thereby causing the switching of the same.
In this way, when each of the component suckers is moved downward, the corresponding pressure switching valve is switched between its two different states. Since the downward movement of each component sucker and the switching of the corresponding pressure switching valve are performed in mechanical synchronism with each other, the timing at which each component sucker is moved downward accurately coincides with the timing at which the NP is supplied to, or removed from, each component sucker. Thus, each component sucker is effectively prevented from failing to suck or mount a CC. In addition, since the upward and downward movements of each component sucker and the switching of the corresponding pressure switching valve can be performed by using a single drive source, the CC mounting system can be produced at reduced cost.
Thus, in the known CC mounting system, the switching of each pressure switching valve to its NP supplying state and the switching of the same to its NP removing state are performed at different positions, respectively, each in mechanical synchronism with the downward movement of the corresponding component sucker. However, there has been no CC transferring device which can switch, at the same position, a pressure switching valve to its NP supplying state and to its NP removing state, each in mechanical synchronism with the movement of a component sucker.